Is there a variable that I missed? let me know if I've left anything out....
New Kettle...cant figure out what happened!?
Started by
*_Guest_Matt C_*
, Dec 28 2009 09:18 PM
8 replies to this topic
#1
*_Guest_Matt C_*
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Posted 28 December 2009 - 09:18 PM
Maybe I missing it but I need your help guys. Just got a new 15.5 pot for xmas. yesterday I calc my boil-off at 1.5 gallons an hour. I have been having trouble hitting my projected volume of 5.5 in the fermenter because of the small size of my old HLT. I have now retired the old HLT and made my old BK the new HLT...all good so far. My first batch with the new BK was a german wheat beer with double decoctions. I figured with:1.5 as my boil-off for 60 min,I rack off the trub in BK and leave about a gallon of "shputz", and grain absorbtion as .2 gallons.I should need 8.2 gallons before the boil to hit my OG and my projected volume of 5.5 into the fermenter.My problem is when I took my "before boil" gravity reading..I noticed that I was either not going to hit my OG or my volume, so i decided to boil for 90 mins to compensate and VIOLA I hit my projected volume and OG! Don't get me wrong I'm happy I hit all my numbers BUT I added on another 30 or so minutes on top of a very long brew day already. My question is WHY did I have to boil for 90 mins in order to hit my numbers!?? Something is not adding up Is there a variable that I missed? let me know if I've left anything out....
Is there a variable that I missed? let me know if I've left anything out....
#2
3rd party JKor
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Posted 28 December 2009 - 10:00 PM
How is grain absorbing wort in your kettle?
Edited by JKoravos, 28 December 2009 - 10:00 PM.
#3
*_Guest_Matt C_*
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Posted 28 December 2009 - 10:07 PM
I meant for mashing...grain absorbing...I see your point. useless info it was a long frustrating brewday today :shock:I failed to mention that I'm following Beersmith's calculations for everything except of course the boil-off ratio.
#4
Dave McG
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Posted 28 December 2009 - 10:09 PM
First, I have to question .2 gallons for grain absorbtion. You didn't say how much grain you used, but I usually count on losing a full gallon for every 8 pounds of grain. This would be in the mash tun though, not the boiler, so it shouldn't be a factor with the boil. Could you have meant hop absorbtion? If I'm reading your post correctly, your preboil gravity was low, and you did a 90 minute boil to compensate. You would expect to hit your gravity numbers then, but get less beer. Gravity Units * volume remains constant, and if your ending gravity and volume were correct, your pre boil volume measurement or your boil off rate must have been incorrect. Either you started with more water than you thought, or your boil off was lower than you expected. Did you actually measure the boil off, or did you compute a projection?
#5
*_Guest_Matt C_*
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Posted 28 December 2009 - 10:39 PM
Nope. I meant grain absorption...which I realize the BK is the wrong place to take that into account for. I have no hop absorption as I am using pellets.I did actually measure the boil off.Yesterday I boiled 3 gallons for 30 mins and ended up with just above 2 gallons,eyeballing about 2.25...give or take. With simple math it should be around 1.5 for 60 mins. It should not matter if I'm boiling 3 gallons of 8 gallons the boil-off should still be pretty much the same logically. However the program I use-Beersmith- Does not calculate this in "normal" terms for example: the program calculates boil off in percentage instead of just putting in what exactly what you boil off actually is. In hindsight I believe I may have over sparged and had to boil off the extra "sparge water" in order to hit the correct SG. To answer I did measure and compute a projection also. I am just wondering is it my calculation thats off or has anyone else had inconsistent results with Beersmith's boil-off calculation tool?
#6
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Posted 28 December 2009 - 10:42 PM
So, did you end up with 8.2 gallons pre-boil?
#7
*_Guest_Matt C_*
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Posted 28 December 2009 - 10:48 PM
Nope it was a little higher ...around 8.5 eyeballing of course. My boilers are marked in gallon increments
#8
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Posted 29 December 2009 - 06:08 AM
I don;t understand the concern. It took you 90 minutes to boil down from 8.5 to 6.5, which is a little less than 1.5 gal/hr.
#9
Thirsty
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Posted 29 December 2009 - 10:19 AM
What Dave was saying is the formula pre-boil gravity units X preboil volume = post-boil gravity units X post-boil volume is constant. So you know the variables of the post-boil to be true, and you knew your pre-boil gravity (which you thought to be low), so you can now determine the EXACT preboil volume. If you know the exact time (90 minutes) then you will know your exact boiloff rate, which sounds slightly higher than anticipated. Example: 1.047 (pre-boil gravity) X Pre-boil volume (unknown) = 1.065 (post-boil gravity) X 6.5 (post-boil volume)or65 X 6.5 = 422.5 so 422.5 / 47 = 8.99 Therefore meaning your preboil gravity would really have been 8.99 instaed of 8.5. Now you know your boiloff rate is actually 1.99 gallons for 90 minutes, not 1.5 gallons. I made up these #s, but if you put yours in the results should be the same.It seems like what you did was accidentally oversparged 1/2 gallon perfectly, because your system boils off 1/2 gallon more than you knew. FWIW I think most systems will vary, but 2 gallons for 90 minutes is very close with a decent rolling but not crazy vigorous boil.
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